Air-cushion for pumps.



F. M. PRESCOTT & E. P. WORDBN. AIR. CUSHION FOR PUMPS. APPLIOATION FILED MAY 1, 190a.

1,035,386, Patented Aug. 13,1912.

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UNITED STATES PATENT OFFICE.

FREDERICK M. PRESCOTT AND EUCLID P. WORDEN, OF MILWAUKEE, WISCONSIN, ASSIGNORS T0 FRED M. PRESCOTT STEAM PUMP COMPANY, OF WEST ALLIS, WISCONSIN, A CORPORATION OF WISCONSIN.

AIR-CUSHION FOR PUMPS.

To all whom it may concern:

Be it known that we, FREDERICK M. Pans- COTT and EUCLID P. WORDEN, citizens of the United States, residing at Milwaukee, in the county of Milwaukee and State of Wisconsin, have invented certain new and useful Improvements in Air-Cushions for Pumps, of which the following is a specification, ref erence being had to the accompanying drawing, forming a part thereof.

This invention relates to-devices for maintaining a uniform flow of liquid from a reciprocating plunger or piston pump. Its main objects are to balance the head or pressure of the liquid, particularly high -pressures, with air under a lower prersure which may be easily produced and maintained; to prevent contact of the air with the liquid and absorption of the former by the latter; and generally to improve the construction and operation of devices of this class.

It consists in certain novel features of construction and in the peculiar arrangement and combination of parts as hereinafter particularly described and pointed out in the claims.

In the accompanying drawing like characters designate the same parts in both figures.

Figure 1 is an axial section of an air cushion embodying the invention; and Fig. 2 is a cross section on the line 2 2, Fig. 1.

This device is designed to take the place of air chambers of the ordinary kind for maintaining a uniform flow of liquid from a reciprocating piston or plunger pump. In the use of the ordinary form of air chamber, where the air is in direct contact with the liquid, it is necessary to supply air from time to time to replace that which has been absorbed by the liquid, and when the liquid pressure maintained is high, it is a difficult matter to supply this air at the requisite pressure. In the present device a movable plunger is in contact with the liquid, and the pressure upon it is resisted by air under pressure acting on a piston of arger area than that of the plunger, and attached directly thereto. This piston is made of such area that air under a resstire which can be readily maintained will balance the higher liquid pressure.

Specification of Letters Patent.

Application filed May 1, 1909.

nection 0, provided with an inwar Patented Aug. 13, 1912.

Serial No. 493,311.

Referring to the drawing, a designates an air cushion cylinder or chamber, having a piston b fitted to work therein, and on one side of the piston adjacent to the upper cylinder head, a compressed air su ply conly opening check valve d, and on the other side of the piston adjacent to the lower head, with an air inlet connection 6, provided with an inwardly opening check valve f for admitting atmospheric air into the lower end of said cylinder or chamber below the piston. The cylinder'is also provided at the lower end with a vent opening controlled by a cock 9. A plunger 1:. of smaller .area than the piston b, is attached thereto at one end and extends therefrom through an opening in the lower cylinder head and a stuifing box a in an open stand or base j, on which the cylinder (1 is mounted and through which the stuffing box is accessible. The stand or base j is attached to a pump (not shown) so that the plunger projects into the discharge chamber or conduit thereof, or is exposed to the pressure of the li uid therein. The piston b is made of sue area relative to that of the plunger k that air under a moderate pressure which can be easily roduced and maintained, acting thereon, wil balance the higher liquid pressure to which the plunger k is subjected.

In the operation of the device, air supplied to the upper end of the cylinder a above the piston I) through the connection a, and prevented from escaping by the check valve (1, resists the upward movement of the iston I; produced by an increase of liqqui pressure upon the plunger h, gradually checkmg and arresting such movement before the iston can come in contact with the up er ey inder head. As the liquid pressure fal s, the compressed air reacting on the piston, forces the plunger h downward, thereby maintaining a substantially constant ressure upon and uniform flow of the liquid as it is discharged by the pump.

The piston b is cushioned in its descent and prevented from coming in violent contact with the lower cylinder head by the air which is drawn into the lower end of the cylinder from the atmosphere through the c eck valve 7 during the upward movement of the piston. The downward movement of the piston may be regulated by adjustment of the vent cock g, and the air in the lower end of the cylinder may be allowed to escape therefrom freely by opening said cock.

Various changes in details of construction and arrangement of parts may be made without departing from the principle and scope of the invention.

We claim:

1. In an air cushion for pumps the combination of a chamber having a compressed air supply connection provided with an inwardly opening check valve adjacent to one end and an air vent and an air inlet provided with an inwardly opening check valve adjacent to the other end, a piston fitted in said chamber between said air supply connection and vent, and a plunger of smaller area connected with said piston and exposed to the liquid subjected to the action of the pump, substantially as described.

2. In an air'cushion for pumps the combination of a cushion chamber provided with a piston and having a compressed air supply connection on one side of the piston and an air inlet connection provided. with an inwardly opening check valve on the other 'side of the piston, and a plunger of smaller area connected with said piston and exposed to the liquid which is subjected to the action of the pump, substantially as described.

3. In an air cushion for pumps the combination of a chamber having a piston fitted therein and on opposite sides of said piston connections provided with inwardly opening check valves, one for compressed air and the other for atmospheric air, and a plunger of smaller area connected with said piston and exposed to the liquid acted on by the pump substantially as described.

.4. In an air cushion for pumps the combination of a cushion chamber provided with a piston and having on one side thereof a compressed air supply connection and onv the other an air supply connection with an inwardly opening check valve and a cock for releasing the air from that end of the chamber, and a plunger of smaller area connected with said piston and exposed to the liquid described.

.on which the pump acts, substantially as W In witness whereof we hereto aflix our signatures in presence of two witnesses.

FREDERICK M. PRESCOTT. EUCLID P. WORDEN. Witnesses:

P. M. TALLoN, R. BOWEN. 

